Wear indicating device for drill bits



Aug. 4, 1953 D. L. DEI. yHOMME. 2,647,729

WEAR INDICATING DEVICE FOR DRILL BITS Filed sept. 22. 1949 /3 r "Y Y ,yf/W

@AT Z @7, Le? l. e//Omme l, INVENTOR.l

B Wal,

ATTORNEYS Patented Aug. 4, 1953 WEAR INDICATING DEVICE FOR DRILL BITS Daniel L. DelHomme, Houston, Tex., assigner to 4 Reed Roller Bit Company, Houston, Tex., a corporation of Texas Application September 22, 1949, Serial No. 117,127 t 6 Claims. (Cl. Z55- 61) This invention relates to new and useful improvements in wear indicating devices for drill bits.

In well drilling, maximum eiiiciency is obtained when the drill bit which is attached to the lower end of the drill pipe is used until it is substantially dull and is no longer capable of performing the drilling operation. It has heretofore been the practice to rely solely upon the driller and his particular knowledge based upon experience with respect to the time when the drill bit has dulled and should be removed, and obviously the human element of error has always been present with the result that in many instances the bit has been pulled or removed from the well prematurely or too long after the drilling bit has lost its eiciency.

It is one object of this invention to provide an improved simplified indicating device which will automatically signal to the surface when the drill bit is worn to a predetermined point, whereby accurate information as to the condition of the drill bit` is made known to the driller or operator.

An important object is to provide an improved wear indicating device for drill bits wherein an opening is formed in the bit body in communication with the drilling iluid which is normally circulated through the bit, together with means closing said opening and arranged to automatically open the same when the bit wears to a predetermined point.

Another object is to provide a wear indicating device of the character described wherein a mechanical closure element is secured to the outer surface of a bit body and normally closes a discharge outlet, with said closure element being adapted to be worn by the abrading action of the formation thereagainst to release said element from its position closing said discharge whereby when the bit wears to a predetermined point the discharge outlet is automatically opened to eleot an abrupt change in the pressure of the circulating fluid.

A further object is to provide a device of the character described wherein a discharge outlet is formed within a bit body and is adapted to be closed by a closure element which is welded or otherwise secured to the bit body in a position closing the outlet; the closure being detached by the abrading action of theformation thereagainst when the bit has worn to a predetermined point whereby the outlet is automatically opened to cause an abrupt pressure variation in the circulating drilling fluid to indicate that the bit has become worn.

Other and further objects of the invention will appear from the description of the invention.`

In the accompanying drawings, which form a part of the instant specication, which are to be read in conjunction therewith, and wherein like reference numerals are used to indicate like parts in the various views:

Figure 1 is an elevation of a drill bit having the improved indicating device constructed in accordance with the invention mounted thereon,

Figure 2 is a bottom view of the drill bit,

Figure 3 is a transverse vertical sectional view of the indicating device taken on the line 3 3 of Figure 1,

Figure 4 is an isometric which is mounted within the discharge outlet, and

Figure 5 is an isometric view of the closure element for closing the discharge outlet.

In the drawings, the numeral I0 designates a bit body which has the usual threaded box II at its upper end whereby the bit may be connected to the lower end of the drill pipe or stem A. The usual fluid cavity or chamber I2 is formed within the bit body and the usual drilling uid circulated downwardly through the drill pipe is directed into the cavity or chamber. Cutting blades I3 are welded or otherwise secured to the lower portion of said body andv drilling iiuid circulating passages I4 extend from the cavity or chamber I2 and discharge from the lower portion of the body adjacent the cutting blades. As illustrated, the blades I3 are disposed transversely of the bit body and have their lower cutting edges |301. located in a plane below the lower end of the body. When the cutting blades have been worn through the drilling operation to the point indicated by the dotted line B or when their vertical edges have been worn to the position indicated by the dotted line C, the bit is dulled and it is desirable that said bit be replaced.

For indicating that the bit blades I3 are worn to either the points B or C, the improved indieating device D is adapted to be mounted on the bit body I0. The indicating device comprises a relatively large opening or outlet I5 which is formed in the wall of thebit body and which establishes communication between the internal chamber or cavity I2 and the area outside of the bit body. The outer portion of the outlet or discharge opening I5 is enlarged in diameter as indicated at I5a. whereby an annular countersunk recess I6 is formed'in the outer portion view of the bushing:

of the body surrounding the opening. A bushing I1 is mounted Within the opening and is welded as indicated at I8 within said opening. The bore of the bushing I1 may have a slush wear ring I9 mounted therein to prevent excessive wear of the bore of the bushing. The bushing l1 has its outer end projecting into the annular recess I6 and this outer portion is formed with a plurality of radially extending projections or lugs 20 which are spaced around the periphery of the bushing. The ends of the bushing are preferably substantially flush with the inner and outer walls of the body I0.

For closing the opening or outlet through the bushing a closure element 2l is provided and this closure element comprises a circular plate or disc 22 having an inwardly directed annular flange 23. An internal annular shoulder 24 is formed at the intersection of the flange 23 and the main body of the plate or disc 22, and this shoulder is arranged to abutthe outer end of the bushing when the closure is applied to said bushing, as will be explained. For interlocking the closure disc or plate 22 on the bushing, the flange 23 is providedwith a pluralityv of inwardly directed lugs 25 which are spaced around the flange, as is clearly shown in Figure 5. The lugs 25 are equal in number t0 the projections 2a on the bushings I1 and in connecting thel closure plate 22 to the bushing the ange 23 is introduced into the annular recess it surrounding the outer end of the flange with. the lugs 25 misaligned with the projections 20. inward movement of the disc or plate 22-v is limitedl` by the engagement of the internal shoulder 2A witlfi'v the end of the bushing and subsequently a rotation is imparted. to the disc and its flange to cause the lugs 25 to engage the projections 2i), as shown in Figure 3. In this position, outward displacen ment ofthe closureI disc from the bushing is prevented. For sealing betweenv the disc and the outer end of the bushing an annular sealing ring 26- is providedv and is confined between the inner surface of the discor plate 22- and the outer end f the bushing, being located adjacent the shoulder 24K.

The closure: disc or plate 2.2 has. an: elongate fastening element 21 welded or otherwise se.- cured thereto andthe fastening element has a depending reduced leg portion 28 which generally follows the curvature of; the bit body' and is adapted to be welded as the outer surface ofv said bit body. The point ofwelding of thel fastening. element 21 tovthe bit' body is preferably in alignment withy the dotted lines B' and C- which indicate the point to which the bit will Wear at the time i-t requires replacement. Thus, until such time as the bit has worn to the=point of the weldy 2,9, the fastening element 2,1 will maintain the closure disc 22A in a position closing the discharge opening through the bushing l1.

The operation of the device is believed-fobvious and in using thesame the closure disc 2211s connectedby means of its lugs 25 and the projecttions 2= of the bushing to said bushing in order to close the opening therethrough. The fasten-v ing element 2.1i. has its lower end welded at 29 to the bit body with the closure disc 22 closing the opening through the bushing.. Thus, the element 21 functions to lock the closurein. a position closing the discharge opening.

Drilling may then proceed in a .normall manner and. since the fastening element 21 is contiguous to-therearsurface ofone ofthe bit-blades,A

indicated vat 2S) to,

said element will not interfere with the normal drilling function of the bit. When the bit wears to a predetermined point as determined by the location of the lower portion 28 of the fastening element and the weld 29, the abrasive action of the formation against the leg portion 28 and against the weld 29 will cause a wearing away of these parts with the result that the fastening element 21 is actually disconnected from the bit body. When this occurs further rotation of the bit will result in a movement of the fastening element sufficient to rotate the fastening lugs 25 of the closure out of alignment with the projections 2B of the bushing. Such misalignment of the lugs and projections will permit the closure disc 22 to be forced outwardly by the drilling fluid which is being circulated downwardly through the drill pipe or stem. It might be noted that the closure disc is constantly exposed to the pressure of this drilling uid which, as is well known, ispumped downwardly through the drill stem and bit body during normal drilling. The outward displacement of the closure disc 22 from the bushing l1 results in an abrupt or I sudden opening of the bushing and allows a sudden escape of the drilling uid through said opening. Because the area of the opening. through the bushing is relativelylarge, the sudden discharge of drilling fluid through said opening results in an` abrupt drop inthe pressure of the uid, and. this pressure drop may be readily observed at the surface. Thus, it is apparent that the abrupt pressure change occuring at the surface indicates when the fluid is discharged through the opening and this is indicative that the drill bit has worn sufficiently to require replacement.

It is obvious that the fastening element 21 which is secured to the closure disc 22 andv which maintains the disc in a position closing the openingv through the bushing may vary in length or shape and may be disposed in any desired plane with respect to the bit blades whereby the device may be arranged to indicate when the bit blades have worn to any predetermined point. The device is extremely simple in construction and comprises only the bushing l1 and the closure element. The disc provides a mechanical closure for the outlet through the bushing which isy maintained in fixed position until such time as a predetermined Wear of thek bit has occurred.

From the foregoing it will be seen that this invention is onel well adapted to attain all of the ends and objects hereinabove set forth, together withy other advantages which are obvious and which are inherent to the structure.

Itr will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and isA Within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in' the accom panying drawings is tobe interpreted as illustrative and not in a limiting sense.`

Having described the invention, I- claim:

1. In combination, a drill bit having cutting elements and also having an opening in its wall, a closurel member for said` opening normally preventing flow of` pressure drillingl fluid from within the body through the opening, coacting means on the closure member and the bitbody for connecting the member in a position closing the opening, said coacting means being disengageable upon rotation of the member relative to the body and a fastening element secured to the closure member and to the bit body for holding the closure member against rotation, said fastening element being adapted to be disconnected from the bit body by the abrasive action of the formation when the cutting elements of the bit have been worn to a predetermined point whereby the closure may be rotated to disengage the coacting means and thereby uncover the opening to allow escape of the pressure drilling fluid through said opening.

2. In combination, a drill bit having cutting elements and having an opening in its wall, an annular bushing within said opening, a closure member detachably connected with the bushing for closing said opening to prevent flow of pressure drilling fluid from within the bit body through the bushing, and a fastening element having one portion secured to the closure member and having another portion adapted to be secured to the bit body for holding the closure member in .its attached position on the bushing with the closure closing said bushing, said fastening element being adapted to be disconnected from the bit body by the abrasive action of the formation when the cutting elements of the bit have been worn to a predetermined point whereby the closure member may be disconnected from the bushing to uncover the opening and allow escape of the pressure drilling uid through said opening.

3. The combination set forth in claim 2 wherein the bushing and the closure member are provided with coacting lugs and projections for detachably fastening the bushing and closure member to each other.

4. The combination set forth in claim 2 together with a wear ring mounted within the bore of the bushing and an annular packing ring for sealing the joint between the closure member and the bushing when the closure member in position on said bushing.

5. The combination as set forth in claim 2 wherein the opening having the bushing therein is located at some distance above the lower portion of the bit and wherein that portion of the fastening element which is secured to the closure comprises a downwardly extending leg portion which is welded to the bit body, the weld being disposed in a plane with respect to the cutting elements of the bit which is at the point where said cutting elements are unduly worn.

6. The combination as set forth in claim 2, wherein the bushing and closure member are formed with radially spaced coasting lugs and projections which are adapted to be interlocked or disengaged by a rotation of the closure member with respect to the bushing, and also wherein the fastening element when secured to the bit body prevents rotation of the closure member to maintain the closure member attached to the bushing, disconnection of said fastening element from the bit body permitting rotation of the closure member to effect disengagement of the coacting lugs and projections.

DANIEL L. DELHOMME.

References Cited in the le of this patent UNITED STATES PATENTS 

